1. Field of the Invention
This invention relates to a liquid chloroprene polymer having a terminal carboxyl group and to a process for the production thereof.
2. Description of the Prior Art
A liquid chloroprene polymer having an active terminal group is a material useful in various fields. Polymers having terminal mercapto groups (e.g., as disclosed in U.S. Pat. No. 3,700,645) and polymers having terminal xanthate groups (e.g., as disclosed in U.S. Pat. Nos. 3,919,281 and 4,051,731, etc.) are known. U.S. Pat. No. 3,969,326 also discloses carboxyl terminated polychloroprene produced by polymerizing chloroprene in the presence of a peroxide initiator having 2 carboxyl groups. These chloroprene polymers are cured with a curing agent such as an amine to provide a rubbery elastomer. The mechanism of curing involves a so-called vulcanization reaction, and the rubbery elastomer, once cured, can no longer be restored to a highly fluid liquid form.
However, the current trend toward expanding the scope of applications and the need for a clean environment in the industrial production and use of adhesives, sealing materials, paints, etc. demands a novel material which is a solvent-free hot-melt elastomer that has sufficient thermo-reversibility that a fluidic liquid form results when the material is hot-melted.